Hyun-boo Lee - Profile on Academia.edu (original) (raw)
Papers by Hyun-boo Lee
International Journal of Precision Engineering and Manufacturing, 2017
Dielectrophoresis (DEP) has been intensively studied to differentiate cells treated with heat or ... more Dielectrophoresis (DEP) has been intensively studied to differentiate cells treated with heat or drugs. To estimate cell properties from DEP experiments, the multi-dimensional relationship between the electrical polarization and the electrical properties of cell components should be understood. However, the limited information extracted from DEP experiments has imposed the burden of approximation of multiple cell properties. In this paper, we present a novel sensitivity analysis to predict cell properties from DEP experimental data. We generated virtual sample cells of various properties in given ranges. Then, the experimental conditions to achieve a higher sensitivity of a polarization factor to cell properties were found through a regressive analysis. Based on the sampling results, cell properties were estimated from the experimental data using a conventional frequency method and a new transition condition method. The estimation predicts the possible properties of cells, which benefits rigorous analysis of cell properties.
Electrolyte-free Amperometric Immunosensor using a Dendritic Nanotip
RSC advances, 2013
Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. S... more Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging. This paper describes a dendritic nanotip used as an amperometric biosensor for highly sensitive detection of target bacteria. A dendritic nanotip is structured by Si nanowires coated with single-walled carbon nanotubes (SWCNTs) for generation of a high electric field. For reliable measurement using the dendritic structure, Si nanowires were uniformly fabricated by ultraviolet (UV) lithography and etching. The dendritic structure effectively increased the electric current density near the terminal end of the nanotip according to numerical computation. The electrical characteristics of a dendritic nanotip with additional protein layers was studied by cyclic voltammetry and I-V measurement in deionized (DI) water. When the target bacteria dielectrophoretically captured onto a nanotip were bound with fluorescence antibodies, the electric current through DI water decreased. Measurement results were consistent with fluorescence- and electron microscopy. The sensitivity of the amperometry was 10 cfu/sample volume (10(3) cfu/mL), which was equivalent to the more laborious fluorescence measurement method. The simple configuration of a dendritic nanotip can potentially offer an electrolyte-free detection platform for sensitive and rapid biosensors.
Nanotip analysis for dielectrophoretic concentration of nanosized viral particles
Nanotechnology, 2013
Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health car... more Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health care, environmental control, military defense, and homeland security. Current detection methods, however, lack either assay speed or sensitivity, mainly due to the nanosized viral particles. In this paper, we compare a dendritic, multi-terminal nanotip ('dendritic nanotip') with a single terminal nanotip ('single nanotip') for dielectrophoretic (DEP) concentration of viral particles. The numerical computation studies the concentration efficiency of viral particles ranging from 25 to 100 nm in radius for both nanotips. With DEP and Brownian motion considered, when the particle radius decreases by two times, the concentration time for both nanotips increases by 4-5 times. In the computational study, a dendritic nanotip shows about 1.5 times faster concentration than a single nanotip for the viral particles because the dendritic structure increases the DEP-effective area to overcome the Brownian motion. For the qualitative support of the numerical results, the comparison experiment of a dendritic nanotip and a single nanotip is conducted. Under 1 min of concentration time, a dendritic nanotip shows a higher sensitivity than a single nanotip. When the concentration time is 5 min, the sensitivity of a dendritic nanotip for T7 phage is 10(4) particles ml(-1). The dendritic nanotip-based concentrator has the potential for rapid identification of viral particles.
Nanotips for single-step preparation of DNA for qPCR analysis
The Analyst, 2013
A single-step concentration and elution method is developed for detection of DNA in buffer, saliv... more A single-step concentration and elution method is developed for detection of DNA in buffer, saliva, and blood. A nanotip capturing DNA using an electric field and capillary action is directly dissolved in buffer for qPCR analysis. The concentration yield and the relative parameters are compared with those of a commercial kit.
Numerical simulation of flow-induced bi-directional oscillations
Journal of Fluids and Structures, 2012
ABSTRACT Flow-induced vibration (FIV) by vortex shedding behind a submerged cylinder can lead to ... more ABSTRACT Flow-induced vibration (FIV) by vortex shedding behind a submerged cylinder can lead to damage of nuclear components. With respect to such a serious scenario, various experiments and numerical simulations have been conducted to predict the vibration phenomena. Especially in simulation, the immersed finite element method (IFEM) is a promising approach to solve fluid-structure interaction problems because it needs less computational resources. In this paper, two-dimensional motions of cylinders are simulated by using IFEM to obtain their vibration characteristics. Three benchmark tests such as flow past a fixed circular cylinder, in-line oscillation of a circular cylinder and flow-induced vibration with uni-directional motion are performed to verify the proposed numerical method. Furthermore, bi-directional motions of two horizontally and vertically arranged cylinders as well as that of a single cylinder in fluid flow are analyzed, and then key findings are fully discussed.
Derivation of mechanical characteristics for Ni/Au intermetallic surface with SAC305 solder
Metals and Materials International, 2013
ABSTRACT Many surface finish methods are used to connect a substrate with the electric components... more ABSTRACT Many surface finish methods are used to connect a substrate with the electric components of IT products in the micro-packaging process, and various types of lead-free solder have been developed as alternative materials to lead-based solder to reduce environmental contamination. However, there has been little research on the mechanical properties of the inter-metallic surface which is generated in the bumping process between the lead-free solder and surface films such as Ni/Au. The present work is to derive the material properties of a Ni/Au inter-metallic surface with SAC305 solder. A series of indentation tests were carried out by changing four nano-scale indentation depths and two strain rates. Also, a reverse algorithm method was adopted to determine the elastic-plastic stress-strain curve based on the load-displacement curve from the indentation test data. As a result of the material characterization effort, the mean elastic modulus, yield strength and strain hardening exponent of IMC with Ni/Au finish were determined.
Sensors, Jan 1, 2012
Various nanowire or nanotube-based devices have been demonstrated to fulfill the anticipated futu... more Various nanowire or nanotube-based devices have been demonstrated to fulfill the anticipated future demands on sensors. To fabricate such devices, electric field-based methods have demonstrated a great potential to integrate one-dimensional nanostructures into various forms. This review paper discusses theoretical and experimental aspects of the working principles, the assembled structures, and the unique functions associated with electric field-based assembly. The challenges and opportunities of the assembly methods are addressed in conjunction with future directions toward high performance sensors.
Microfluidics and …, Jan 1, 2012
Simple, high-yield concentration of DNA is important for high-throughput genetic analysis and dis... more Simple, high-yield concentration of DNA is important for high-throughput genetic analysis and disease diagnosis. Glass-based microfilters are popular but the process requires centrifugation steps with cumbersome chemical processes. As an alternative, a concentration method using an electric field has been explored previously, but with limited efficiency. In this paper, electric field-induced concentration and capture of DNA are studied by using high-aspect-ratio microtips coated with a gold layer. The microtips are immersed longitudinally into a solution of 100 lL containing k-phage DNA. After DNA concentration using an electric field, the microtips are withdrawn from the solution. Under AC-and biased AC fields, DNA is concentrated by electrophoresis (EP), dielectrophoresis (DEP), and electroosmotic flow (EOF). To reduce capillary effects in the withdrawal process, the microtips are coated with positively charged poly-L-lysine (PLL). The pattern of captured DNA is analyzed by fluorescence microscopy. DEP attracts DNA molecules at the edges of microtips, where the highest gradient of electric field exists. EP attracts DNA onto the surface of microtips following the vectors of an electric field. EOF generates vortexes that deliver DNA onto microtips. Using this method, 85% of DNA is captured on the PLL-coated microtips after three sequential captures. The concentration mechanism can potentially facilitate rapid and simple preparation of DNA for downstream analysis.
Enhanced bioreaction efficiency of a microfluidic mixer toward high-throughput and low-cost bioassays
Microfluidics and …, Jan 1, 2011
Abstract Microscale bioreactors are an important tool in performing bioassays. The speed and effi... more Abstract Microscale bioreactors are an important tool in performing bioassays. The speed and efficiency of these devices is often limited by the rate of reagent mixing. In spite of the various micromixing approaches, the coupled mixing/reaction process has yet to be ...
Characterization of Elastic‐plastic Material Properties for IMC Layer of ENEPIG by Using Reverse Algorithm
AIP Conference …, Jan 1, 2010
Recently, the reliability assurance of lead‐free solder to prevent environmental contamination is... more Recently, the reliability assurance of lead‐free solder to prevent environmental contamination is quite important issue for chip‐scale packaging. Although lots of efforts have been devoted to the solder undergone drop, shear and creep loads, there was a little research on IMC ...
International Journal of Precision Engineering and Manufacturing, 2017
Dielectrophoresis (DEP) has been intensively studied to differentiate cells treated with heat or ... more Dielectrophoresis (DEP) has been intensively studied to differentiate cells treated with heat or drugs. To estimate cell properties from DEP experiments, the multi-dimensional relationship between the electrical polarization and the electrical properties of cell components should be understood. However, the limited information extracted from DEP experiments has imposed the burden of approximation of multiple cell properties. In this paper, we present a novel sensitivity analysis to predict cell properties from DEP experimental data. We generated virtual sample cells of various properties in given ranges. Then, the experimental conditions to achieve a higher sensitivity of a polarization factor to cell properties were found through a regressive analysis. Based on the sampling results, cell properties were estimated from the experimental data using a conventional frequency method and a new transition condition method. The estimation predicts the possible properties of cells, which benefits rigorous analysis of cell properties.
Electrolyte-free Amperometric Immunosensor using a Dendritic Nanotip
RSC advances, 2013
Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. S... more Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging. This paper describes a dendritic nanotip used as an amperometric biosensor for highly sensitive detection of target bacteria. A dendritic nanotip is structured by Si nanowires coated with single-walled carbon nanotubes (SWCNTs) for generation of a high electric field. For reliable measurement using the dendritic structure, Si nanowires were uniformly fabricated by ultraviolet (UV) lithography and etching. The dendritic structure effectively increased the electric current density near the terminal end of the nanotip according to numerical computation. The electrical characteristics of a dendritic nanotip with additional protein layers was studied by cyclic voltammetry and I-V measurement in deionized (DI) water. When the target bacteria dielectrophoretically captured onto a nanotip were bound with fluorescence antibodies, the electric current through DI water decreased. Measurement results were consistent with fluorescence- and electron microscopy. The sensitivity of the amperometry was 10 cfu/sample volume (10(3) cfu/mL), which was equivalent to the more laborious fluorescence measurement method. The simple configuration of a dendritic nanotip can potentially offer an electrolyte-free detection platform for sensitive and rapid biosensors.
Nanotip analysis for dielectrophoretic concentration of nanosized viral particles
Nanotechnology, 2013
Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health car... more Rapid and sensitive detection of low-abundance viral particles is strongly demanded in health care, environmental control, military defense, and homeland security. Current detection methods, however, lack either assay speed or sensitivity, mainly due to the nanosized viral particles. In this paper, we compare a dendritic, multi-terminal nanotip ('dendritic nanotip') with a single terminal nanotip ('single nanotip') for dielectrophoretic (DEP) concentration of viral particles. The numerical computation studies the concentration efficiency of viral particles ranging from 25 to 100 nm in radius for both nanotips. With DEP and Brownian motion considered, when the particle radius decreases by two times, the concentration time for both nanotips increases by 4-5 times. In the computational study, a dendritic nanotip shows about 1.5 times faster concentration than a single nanotip for the viral particles because the dendritic structure increases the DEP-effective area to overcome the Brownian motion. For the qualitative support of the numerical results, the comparison experiment of a dendritic nanotip and a single nanotip is conducted. Under 1 min of concentration time, a dendritic nanotip shows a higher sensitivity than a single nanotip. When the concentration time is 5 min, the sensitivity of a dendritic nanotip for T7 phage is 10(4) particles ml(-1). The dendritic nanotip-based concentrator has the potential for rapid identification of viral particles.
Nanotips for single-step preparation of DNA for qPCR analysis
The Analyst, 2013
A single-step concentration and elution method is developed for detection of DNA in buffer, saliv... more A single-step concentration and elution method is developed for detection of DNA in buffer, saliva, and blood. A nanotip capturing DNA using an electric field and capillary action is directly dissolved in buffer for qPCR analysis. The concentration yield and the relative parameters are compared with those of a commercial kit.
Numerical simulation of flow-induced bi-directional oscillations
Journal of Fluids and Structures, 2012
ABSTRACT Flow-induced vibration (FIV) by vortex shedding behind a submerged cylinder can lead to ... more ABSTRACT Flow-induced vibration (FIV) by vortex shedding behind a submerged cylinder can lead to damage of nuclear components. With respect to such a serious scenario, various experiments and numerical simulations have been conducted to predict the vibration phenomena. Especially in simulation, the immersed finite element method (IFEM) is a promising approach to solve fluid-structure interaction problems because it needs less computational resources. In this paper, two-dimensional motions of cylinders are simulated by using IFEM to obtain their vibration characteristics. Three benchmark tests such as flow past a fixed circular cylinder, in-line oscillation of a circular cylinder and flow-induced vibration with uni-directional motion are performed to verify the proposed numerical method. Furthermore, bi-directional motions of two horizontally and vertically arranged cylinders as well as that of a single cylinder in fluid flow are analyzed, and then key findings are fully discussed.
Derivation of mechanical characteristics for Ni/Au intermetallic surface with SAC305 solder
Metals and Materials International, 2013
ABSTRACT Many surface finish methods are used to connect a substrate with the electric components... more ABSTRACT Many surface finish methods are used to connect a substrate with the electric components of IT products in the micro-packaging process, and various types of lead-free solder have been developed as alternative materials to lead-based solder to reduce environmental contamination. However, there has been little research on the mechanical properties of the inter-metallic surface which is generated in the bumping process between the lead-free solder and surface films such as Ni/Au. The present work is to derive the material properties of a Ni/Au inter-metallic surface with SAC305 solder. A series of indentation tests were carried out by changing four nano-scale indentation depths and two strain rates. Also, a reverse algorithm method was adopted to determine the elastic-plastic stress-strain curve based on the load-displacement curve from the indentation test data. As a result of the material characterization effort, the mean elastic modulus, yield strength and strain hardening exponent of IMC with Ni/Au finish were determined.
Sensors, Jan 1, 2012
Various nanowire or nanotube-based devices have been demonstrated to fulfill the anticipated futu... more Various nanowire or nanotube-based devices have been demonstrated to fulfill the anticipated future demands on sensors. To fabricate such devices, electric field-based methods have demonstrated a great potential to integrate one-dimensional nanostructures into various forms. This review paper discusses theoretical and experimental aspects of the working principles, the assembled structures, and the unique functions associated with electric field-based assembly. The challenges and opportunities of the assembly methods are addressed in conjunction with future directions toward high performance sensors.
Microfluidics and …, Jan 1, 2012
Simple, high-yield concentration of DNA is important for high-throughput genetic analysis and dis... more Simple, high-yield concentration of DNA is important for high-throughput genetic analysis and disease diagnosis. Glass-based microfilters are popular but the process requires centrifugation steps with cumbersome chemical processes. As an alternative, a concentration method using an electric field has been explored previously, but with limited efficiency. In this paper, electric field-induced concentration and capture of DNA are studied by using high-aspect-ratio microtips coated with a gold layer. The microtips are immersed longitudinally into a solution of 100 lL containing k-phage DNA. After DNA concentration using an electric field, the microtips are withdrawn from the solution. Under AC-and biased AC fields, DNA is concentrated by electrophoresis (EP), dielectrophoresis (DEP), and electroosmotic flow (EOF). To reduce capillary effects in the withdrawal process, the microtips are coated with positively charged poly-L-lysine (PLL). The pattern of captured DNA is analyzed by fluorescence microscopy. DEP attracts DNA molecules at the edges of microtips, where the highest gradient of electric field exists. EP attracts DNA onto the surface of microtips following the vectors of an electric field. EOF generates vortexes that deliver DNA onto microtips. Using this method, 85% of DNA is captured on the PLL-coated microtips after three sequential captures. The concentration mechanism can potentially facilitate rapid and simple preparation of DNA for downstream analysis.
Enhanced bioreaction efficiency of a microfluidic mixer toward high-throughput and low-cost bioassays
Microfluidics and …, Jan 1, 2011
Abstract Microscale bioreactors are an important tool in performing bioassays. The speed and effi... more Abstract Microscale bioreactors are an important tool in performing bioassays. The speed and efficiency of these devices is often limited by the rate of reagent mixing. In spite of the various micromixing approaches, the coupled mixing/reaction process has yet to be ...
Characterization of Elastic‐plastic Material Properties for IMC Layer of ENEPIG by Using Reverse Algorithm
AIP Conference …, Jan 1, 2010
Recently, the reliability assurance of lead‐free solder to prevent environmental contamination is... more Recently, the reliability assurance of lead‐free solder to prevent environmental contamination is quite important issue for chip‐scale packaging. Although lots of efforts have been devoted to the solder undergone drop, shear and creep loads, there was a little research on IMC ...